The MRI apparatus is an image diagnostic apparatus which excites nuclear spin of an object set in a static magnetic field with a RF (radio frequency) signal having the Larmor frequency magnetically and reconstruct an image based on MR (magnetic resonance) signals generated due to the excitation.
In MRI, various prepulses are applied as RF pulses prior to data acquisition for obtaining an image having a desired contrast. For example, in a magnetic resonance angiography (MRA) which performs imaging of blood vessels, a spin labeling pulse (also referred to a tagging pulse or a labeling pulse) is applied for obtaining a difference in contrast between a blood flow and a background tissue.
The spin labeling pulse is a prepulse for tagging spins including in a fluid such as a blood and a cerebrospinal fluid (CSF) which flows in an imaging section. Especially, the spin labeling pulse for blood is called an arterial spin labeling (ASL) pulse.
A time-spatial labeling inversion pulse (t-SLIP) is known as a representative spin labeling pulse used for a non-contrast-enhanced MRA. The t-SLIP consists of a region non-selective inversion recovery (IR) pulse and a region selective IR pulse. The region selective IR pulse can be set arbitrarily and independently from an imaging region. Therefore, when a labeling region is labeled with a region selective IR pulse, so that MR signals from blood in a specific region are enhanced, while MR signals are suppressed with a non-selective IR pulse, the blood which flows out of the labeling region after an inversion time (TI) can be depicted selectively as a high signal intensity part.
Note that, the region non-selective IR pulse can be switched between ON and OFF. When the region non-selective IR pulse is OFF, signals from blood included in a labeling region are suppressed by applying a region selective IR pulse. Therefore, the blood which flows out of the labeling region after a TI is depicted as a low signal intensity part.
Other than the t-SLIP as described above, an RF pulse such as a saturation pulse is used for adjusting a contrast. A presaturation (Presat) pulse which is applied as an RF prepulse is a prepulse for suppressing signals from a desired matter by saturating spins in the desired matter.
The RF prepulses, which are applied for adjusting a contrast, including the t-SLIP and the Presat pulse, can be combined mutually. Specifically, MR images having various contrasts can be acquired by applying same or different types of region selective RF prepulses or region non-selective RF prepulses prior to a data acquisition.
Accordingly, for setting these RF prepulses, a graphical user interface (GUI), which displays a TI of a target IR pulse with a schematic diagram showing an R wave interval of an electro cardiogram (ECG) signal used as a synchronizing signal, is used as a setting screen of imaging conditions. Furthermore, a GUI for setting respective application regions of RF prepulses with displaying the application regions is used as a locator.
It is desirable to provide a GUI clearer for a user in order to set applications of plural RF prepulses such as IR pulses easily.
Accordingly, it is an object of the present invention to provide a magnetic resonance imaging apparatus and a magnetic resonance imaging method which can indicate a setting status of plural RF prepulses to a user more clearly in a case of setting applications of the RF prepulses.